Personal wash compositions are available in various forms such as soap bars, transparent soap bars including cast-bars, liquid soaps including liquid hand wash compositions, creams and gel based products. Commercial soap compositions have one or more “soaps”, which has the meaning as normally understood in the art; salts of mono carboxylic fatty acids. The counterions of the salts are generally sodium, potassium, ammonium and alkanolammonium ions, but other suitable ions known in the art may also be used. Compositions based on soaps, i.e. soap bars generally contain over about 70% by weight alkali metal salt of fatty acids, which accounts for the total fatty matter (TFM), the remainder being water (about 10-20%) and other ingredients such as metal ion chelators, color, perfume, preservatives etc. Structurants and fillers are also frequently added to such compositions in small amount to replace some of the soap, while retaining the desired properties of the product. Soaps having TFM content of about 70 are called “toilet soaps”, whereas those having TFM of about 40 are called “bathing bars”.
Synthetic surfactants are sometimes, also added to soap based personal wash compositions to achieve better product performance. On the other hand, compositions based entirely on synthetic surfactants are also known in the art.
There are several types of microorganisms, such as bacteria, virus and molds, present in the atmosphere, some of which prefer to live and multiply on human skin. Some of these organisms that reside on human skin, cause undesirable conditions such as body odor, pimples and acne, which are cosmetically un-acceptable to people. These conditions are further aggravated by hot and humid climatic conditions. One way to get rid of these microorganisms residing on the skin is to wash them off, while having bath or while washing hands, preferably using a washing composition, such as soap.
Soaps per-se, are known to have possess antimicrobial properties. In addition, specially formulated germicidal soaps are also known in the art, which are used to treat serious skin disorders like scabies. To provide antibacterial benefits through soap compositions, it is necessary to add germicides or antibacterial agents to the formulation. Thus, for example, bars containing antimicrobials such as triclosan (i.e., 2,4,4′-trichloro-2′-hydroxy-diphenylether; TCN) and triclocarbanilide; TCC are known. Especially useful are antibacterial cleansing compositions, such as soap bars, that typically are used to cleanse the skin and to destroy bacteria and other microorganisms present on the skin, especially the hands, arms, and face of the user. Antibacterial compositions are used, for example, in the health care industry, food service industry, meat processing industry, and by individual consumers. The widespread use of antibacterial compositions indicates the importance that consumers place on controlling the population of bacteria and other microorganism on the skin.
Antibacterial personal wash compositions have also been reported in prior art.
JP2003138295 (Pelican Soap Company) describes a molded solid soap having 1% bentonite, 95.9% soap base material, 1% medical carbon, 1% kaolin, 1.00 wt. % perfume, and 1% papain powder. This composition has antibacterial properties. A drawback of such a composition is the use of medical carbon and enzyme (papain), which are difficult to incorporate in soaps. Another drawback is that the black particles of medical carbon, present in the soap bar would be readily visible; therefore it is likely that the product would lack consumer appeal.
U.S. Pat. No. 5,403,506 (Church & Dwight Co., Inc, 1995) provides a deodorant detergent composition containing a soap or synthetic surfactant and Zinc oxide having particle size less than 10 microns as a deodorizing component. It is further preferred that the composition also contains a minor amount of sodium bicarbonate. The composition is useful as a personal toilet soap or detergent composition.
U.S. Pat. No. 5,062,994 (Diana Imperatori, 1991) describes a moisture free skin cleansing composition in tablet form comprising a skin cleansing powder selected from certain anionic or non-ionic surface active agents and at least one absorbing powder selected from the group consisting of cellulose, modified starches, kaolin, bentonite, talc, silicates, silica, magnesium carbonates, magnesium hydroxides, attapulgite, montmorillonite and mixtures thereof, a lubricating material and a disaggregating substance.
Among the fatty acid soaps, Lauric acid soaps are known, and products that contain higher proportion of lauric acid soaps in the formulation are available. These soaps typically contain about 25 to 35% Lauric soaps, in combination with other non-Lauric soaps.
Zinc oxide is an antimicrobial active, reported in several personal wash compositions.
The present inventors have surprisingly found that a combination of Lauric acid soap and Zinc oxide, when used together in a personal wash composition, works synergistically and provides superior benefits in controlling the microbial activity on the surface of the skin by efficient cleaning of the skin. It has therefore become possible to prepare an efficacious antibacterial personal wash composition by employing lower levels of zinc oxide to demonstrate antibacterial benefit.
The present invention thus addresses the need for personal wash compositions that exhibit enhanced antibacterial properties, without compromising on the desired sensorials of soap usage by the consumer.